In drafting, the speed and accuracy of representation are of the essence. The practice of reducing or enlarging an article in size for representation, or scaling off, is often particularly time-consuming. In drafting, a plurality of lines of angular relationship must often be drawn, such as with the usual protractor or other such drafting aids. Often, a great many parallel lines equidistant from a center point must be drawn. The established procedures of measuring to and from a center point and drawing lines spaced equidistantly therefrom are time-consuming and subject to error.
The principal objects of the present invention are: to provide a drawing apparatus having a compass rose plate therewith for establishing angular relationships; to provide such a drawing apparatus having means therewith for scaling off; to provide such a drafting apparatus having parallel rule means therewith for establishing parallel lines; to provide such a drawing apparatus having measurement scales therewith to determine the linear distance from a center point of equidistant lines; to provide such a drawing apparatus having an expansible and contractible parallelogram structure positioned atop a compass rose plate; to provide such a drawing apparatus having a carriage frame therewith supporting an expansible and contractible parallelogram structure for selective placement of the parallelogram structure over portions of a compass rose plate; to provide a drawing apparatus having a plurality of drafting aids adapted for use with the drawing apparatus; to provide such a drawing apparatus which may be disassembled and quickly reassembled; to provide such a drawing apparatus which may be easily adjusted to accomodate different thicknesses of drawing paper; and to provide such a drawing apparatus which is relatively inexpensive, sturdy and efficient in use, and particularly well adapted for the intended purpose.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein are set forth, by way of illustration and example, certain embodiments of this invention.